The present invention is related to a lift valve, particularly for process technology, with a valve housing consisting of at least one valve housing component, with at least a first and a second connecting sleeve, which are connected to the valve housing component and produce a connection to the interior space thereof, with a connection opening arranged in the valve housing between the connecting sleeves, in or on which connection opening a seating area is formed, with a translationally displaceable monolithic closing element that co-operates with the seating area and controls the connection opening, with one single actuation rod fastened on the closing element and being sealingly guided out of the valve housing through a housing opening of the same in front of the connection opening and being connected to a driving piston of an actuator, with a lantern housing connecting the valve housing with the actuator, with the actuator which has in a drive housing the driving piston that is displaceable against the force of a driving spring upon pressurization with a pressure medium, and with the actuation rod, which is enlarged in its cross section at least in the penetration region with the valve housing, such that it accommodates a part of the driving spring at the closing element side thereof in a pot-shaped recess.
The lift valve of the kind characterised in the beginning has the necessary features of a shut-off valve, wherein at least one component of the translational opening- and closing movement of its closing element realised as a seat disk is directed vertically against a seating area. Yet however, the lift valve can also be realised as a slide valve in the context of the above embodiment, wherein the closing element, realised as a slide piston, slides along a cylindrical seating area in its translational opening- and closing movement. A closing element seal disposed in the seating disk co-operates axially or axially/radially with the associated seating area (seal in the so-called pressure engagement), while a closing element seal disposed in the slide piston co-operates radially with the associated cylindrical seating area (seal in the so-called sliding engagement). The translational opening- and closing movement of the respective closing element is generated via a piston drive pressurized by a pressure medium, preferably via a pneumatically pressurized one, wherein the restoring movement of a driving piston is normally performed by a spring, preferably a helical spring. With respect to the closing element and the associated seating area, the piston drive may work in a spring-closed or in a spring-opened manner. In order to reduce the opening forces of the shut-off valve, the actuation rod of the closing element can be realised in the form of a so-called pressure compensation piston in the region of its penetration through the valve housing, so that the pressure forces from the fluid, present in the valve housing (from the product, e.g.) and acting on the closing element in the lifting direction, experience a partial to complete compensation on the projected front surface of the pressure compensation piston.
Process valves of the kind described above exist in a plurality of constructions, a so-called lantern housing being disposed between the valve housing and the actuator for safely separating a fluid present in the valve housing from the pressure medium that pressurizes the driving piston in the actuator. With respect to the vertical standard position of the valve, the opening movement of the process valve takes place either towards the upside or towards the downside, so that one speaks of a valve opening towards the upside or towards the downside. Because an overall height as small as possible towards the downside is normally desired, the actuator is disposed above the valve housing in the standard case.
A decisive criterion of choice for process valves of the kind in question is not only its overall height towards the downside, but also that towards the upside. The latter is essentially determined by the realisation of the lantern housing and the actuator, the latter requiring at least an overall height for the spring(s) and for the valve stroke in form of the stroke of the driving piston (for instance according to DE 30 06 409 A1).
Actuators for lift valves are furthermore known which have two closure parts or closing elements that are movable with respect to each other (in the following, the designations “closure part” and “closing element” are used synonymously) and are designated as so-called double seat valves, in which the axial extension of the lantern housing, the length of the necessary springs in the assembled condition and if applicable the stroke of the driving piston or the driving pistons each sum up completely. Such a double seat valve that opens towards the upside, towards the actuator, is described in DE 26 23 039 A1. In order to produce a pressing force between the two closing elements in the opened position, this double seat valve requires a second spring whose length sums up to that of the main spring. A double seat valve in this regard which opens towards the downside, away from the actuator, is known from DE 31 06 578 A1. Here, in order to save overall height, the second spring is housed in the constructional space of the main spring.
In the double seat valves mentioned above, the actuation rods of the closing elements are normally realised in the form of so-called pressure compensation pistons, in particular then when the latter are realised as slide pistons. In order to ensure sufficient compensation of the forces on the respective closing element by corresponding counter-forces on the associated pressure compensation piston, these pressure compensation pistons are mostly enlarged with respect to cross section up to the effective projected cross section of the associated closing element. The big opening areas through the valve housing caused by this make the sealing of these pressure compensation pistons difficult at the one hand, but on the other hand, the pressure compensation piston offers constructional space in its interior for an overall height saving accommodation of the springs of the actuator.
A solution in this regard is known for instance from EP 0 834 689 A1. Here, a spring packet forming the main spring and consisting of two concentrically interlaced helical springs, is arranged in a spring cage, which engages into a pressure compensation piston formed on the upper closing element and ends at its lower end, with its fixed spring abutment, on the inner space of the neighbouring valve housing. In the opened position of the double seat valve which opens towards the downside, it becomes evident that the lower end of the spring cage acting as a fixed spring abutment cannot be displaced with respect to the valve housing, and only the upper end of the spring packet experiences an axial displacement corresponding to the valve stroke during the opening process of the double seat valve. So, it becomes clear that the overall height of the actuator is at least determined by the extent of the axial extension of the biased spring packet in the closed position of the valve.
In a double seat valve described in EP 0 039 319 B2, two springs in the pressure compensation piston that sum up in their constructional length are arranged on the upper closing element, which engage up to the seat region, while the pressure compensation piston on the lower closing element acts a driving piston of the actuator, and thus, no additional constructional height is required for the stroke of the driving piston. Through this construction of the upper pressure compensation piston with respect to the arrangement of the springs, overall height is saved in fact on the one hand, but on the other hand this leads to cross section narrowing in the upper valve housing. In order to compensate this narrowing, an opening area of the valve housing greater than that in the seat region between the two valve housing components is in turn necessary at least in the penetration region of the associated pressure compensation piston. A lantern housing in the classical sense is not provided; instead, a so-called rinsing lock prevents the mixing of pressure medium in the actuator and fluid in the valve housing.
From EP 0 174 384 B1, a double seat valve developed further from EP 0 039 319 B2 is known, in which is provided, in addition to the older double seat valve, amongst others a partial stroke of a driving piston for the seat cleaning of the upper closing element, which necessitates an additional overall height.
The principle described above for the arrangement of one or plural springs within a spring cage, which engages with its lower end acting as a fixed spring abutment into a pressure compensation piston of a closing element that opens towards the downside, is also used for lift valves which have one single closure part or closing element, respectively. A lift valve relating to this is known under the company-generated designation Kode 8222 from the company document HOVAP Varioflow pneumatische Prozessventile, HOVAP INTERNATIONAL (HOLLAND) B. V., Sneek (NL), VAC.9.86.D.
In fact, this known solution saves more overall height than such solutions where the inner space of the pressure compensation piston is not used or cannot be used for accommodating the driving spring(s). However, there remains the general disadvantage that the entire length of the driving spring, namely in a biased length as the same is required in the closed position of the lift valve, must be accommodated by the actuator. Moreover, like in the present case, the overall height of the valve in the region of its actuator still comprises the full valve stroke in addition, because a rod connected to the closing element is guided towards the upside through the front side of the actuator, amongst others in order to guide the closing element.
Even the manner how the valve housing and the actuator are connected via the lantern housing exerts an influence on the overall height of the respective process valve, this influence rather being small in this. More decisive in this context is the influence of this connection on the expense for mounting and dismounting and on the cost for realising this connection. Since a tenfold of years, essentially the three kinds of such a connection shortly delineated below are being realised.
On the one hand, it is dealt with a connection via flanges that are screwed together with each other. The documents EP 0 646 741 B1 and EP 0 174 384 B1 each show a connection related to this between valve- and lantern housing in a double seat valve. This connection is time-consuming in mounting and dismounting, and a rotation between valve housing and drive is possible only according to the extent of the circumferential separation of the connecting screws.
On the other hand, in the majority of all the process valves of the kind in question, the so-called clamp flange connection is preferred today, which is disclosed for instance in DE 200 06 594 U1 (process valve with one single closing element) or in DE 38 35 944 A1 or in EP 0 834 689 A1 (both dealing with a double seat valve). In these, the housing components that are to be connected with each other each have a so-called clamp flange, which is conically inclined radially towards the outside at its outside flank. The respective pair of clamp flanges, which symmetrically tapers towards the outside, is held together by a divided clamping ring complementary to the inclined flanks and covering almost 360 degrees, wherein the two clamp ring halves are connected to each other and held together either via an articulation at the one side and a screw joint at the other side, or via two screw joints. A connection related to this is friendly for mounting and dismounting and it is possible to position the drive with respect to the valve housing in every arbitrary position. However, the cost for such a connection is higher than with a screwed flange connection.
Finally, it is known to perform the connection between valve- and drive housing via a screw joint (for instance a so-called pipe screwing according to DIN 11851 or DIN 11864) (WO 2007/128360 A1). Here, the lantern housing normally carries the groove nut, and the exterior thread is formed on the valve housing. This connection is preferably used in sterile unit operation processes, because the groove nut offers less contact surfaces towards the outside for contamination than a screwed flange or clamping connection. The cost are highest compared with the two kinds of connection mentioned above; however, the disadvantages of the kind mentioned above are not existent.
The document DE 90 13 788 U1 describes a connecting piece for an auxiliary apparatus for the heat- and water supply, in particular for a water counter, a heat counter or a filter top, with a shut-off valve that is rotatably mounted in a housing between a passage position and a closing position, and with a top for the auxiliary apparatus that is adapted to be detachably connected to the housing. Here, the top is connected to the housing by way of a bayonet joint, in which a bolt is guided in an L-shaped groove. The top is coupled to the shut-off valve in such a way (this means concretely a catching connection in the circumferential direction, not a clamp connection in the axial direction) that when mounting the top on the housing, the shut-off valve is opened, and closed when it is being dismounted.
In WO 2007/128 360 A1 are described housing aggregations for monitoring-, control and regulation systems for a process valve. The respective housing aggregation consists of a series of individual housing tops, which are connected to each other by way of a bayonet joint like connection mechanism.
It is the objective of the present invention to provide a process valve acting as a lift valve of the kind described in the beginning with an uniform closure part or closing element, respectively, (irrespective whether in one or plural parts), which altogether features a shorter overall height than all the known and comparable valves relates to this, which is very simple in its construction and which is furthermore applicable to the different embodiments like shut-off-, tank bottom- or reversing valves.